Luminescence dating methods are widely used to date coastal sediments, while luminescence tracing methods are an upcoming approach to reconstruct coastal sediment pathways. Both methods rely on subaqueous resetting (bleaching) of luminescence signals and would benefit from quantification of this process in the natural coastal environment. We describe the set-up and outcomes of an in situ subaqueous bleaching experiment for luminescence signals of K-feldspar grains in the Dutch Wadden Sea. We deployed a full-day bleaching field experiment with irradiated feldspar samples tethered to a pole at various positions within and above the water column to quantify (1) the bleaching potential, that is, the light intensity and spectrum as a function of time, depth and tidal stage, and (2) the bleaching efficiency, that is, the degree of bleaching of infrared stimulated luminescence (IRSL) and post-infrared IRSL (pIRIR) signals measured at 150, 225 and 290°C after a full day of light exposure above and below water. Our bleaching-potential results show that the strongest subaqueous light attenuation took place during low tide when sediment concentrations are the highest. We also observed stronger attenuation of the ultraviolet part of the spectrum compared to other parts of the spectrum. Our bleaching-efficiency results show that bleaching reduces with depth, that pIRIR signals bleach slower than IRSL signals underwater and that bleaching efficiency reduces with pIRIR measurement temperature. None of the investigated signals were fully reset after 13.5 hours of light exposure, even for subaerially exposed samples. Our work provides the first quantitative data on pIRIR bleaching in a natural subaqueous environment, which is relevant for K-feldspar-based luminescence dating and tracing applications.

The bleaching of cottonseed oil by alumina-pillared (Al-pillared) acid-activated clays was investigated. Acid activation of a Ca-rich montmorillonite (CMS STx-1) following treatment with 1, 4, and 8 eq/L sulfuric-acid solutions, as well as subsequent pillaring with alumina, produces new materials. These materials have bleaching properties dependent upon the extent of activation of the clay prior to pillaring. The pillared acid-activated montmorillonites possessed higher bleaching efficiency compared to pillared products of the untreated clay. Mild activation of the montmorillonite matrix, pillaring with the Keggin ion [Al13O4(OH)24(H2O)12]7+, and calcination temperatures to 500°C produced materials with the best fractional degree of bleaching. Direct comparison to the performance of a commercial bleaching earth (Tonsil Optimum 214, Sud-Chemie AG. Moosburg, Germany) shows that the efficiency of the Al-pillared acid-activated montmorillonite may be improved. The optimization of the bleaching process is achieved via a judicious utilization of intermediate surface area, relatively high acidity, and enhanced pore volume.

High-whiteness kaolinite mining reserves are scarce. In some locations, it is necessary to remove material to access them (adding to the cost). Therefore, processes have been developed to eliminate contaminants, such as iron, and provide alternatives to the used contaminated materials that, after being treated, meet quality criteria. In our previous research, we developed an electrochemical process for kaolin whitening at the laboratory level and bench scale, demonstrating the reaction mechanisms that occur during the removal of iron from kaolin. However, the geometry used at the laboratory level does not present the most suitable position for the electrodes. Therefore, in the present study, we focused on the geometry and the function of the electrodes. This is necessary during the escalation process to reach the pilot-scale level. The study was carried out using computer-aided engineering in the COMSOL Multiphysics computer program and by analysing the distribution of the electric potential and the electric current of the geometries considered while performing the scaling. The results indicated that the change in the anode position from perpendicular to parallel to the discs improved the distribution of electric current density on the cathode surface and so increased the elimination of iron through electrochemical deposition. Similarly, to reduce the amount of material used in the construction of the reactor, the anode-size effect was analysed, revealing that relatively small anodes improved the distribution of electric current density over the entire surface of the electrode and not only at the edges.

Clomazone is a widely used herbicide in California water-seeded rice for control of bearded sprangletop and watergrass. Generally, clomazone is applied to a flooded rice field at day of rice seeding. However, interest exists among growers to delay the clomazone application. Weather variability may encourage growers to practice Leathers’ method. Leathers’ method is the practice of draining the field 1 to 2 d after air seeding to encourage better and more uniform seedling establishment, then reflooding back to a 10- to 15-cm flood 4 to 7 d later. Therefore the objective of this study was to evaluate grass weed control and rice response at four rates of clomazone, applied at two timings: at day of seeding (DOS) in a continuous 10-cm flood and after Leathers’ method. This study was conducted in 2019 and 2020 at the Rice Experiment Station in Biggs, CA. In 2019, there were no difference across clomazone rates on control of bearded sprangletop independent of application timing used; however, in 2020, bearded sprangletop control with clomazone applied after Leathers’ method was 70% to 71% across clomazone rate by 60 d after treatment (DAT), compared to 92% to 97% in the DOS applications. Watergrass control was 100% in 2019 across clomazone rate and application timing. However, in 2020, watergrass control was greater at the DOS application at 54% to 71%. Clomazone applied at the 0.7 kg ha−1 Leathers’ method resulted in 84% bleaching by 14 DAT and was similar across all Leathers’ method clomazone applications and the 0.7 kg ha−1 DOS application. There was no rice grain yield difference among all clomazone-treated plots, with the exception of the 0.7 kg ha−1 Leathers’ method interaction with the DOS applications.

Acid activation was carried out by heating muds prepared from Ca-rich bentonite (CaB), sulfuric acid (H2SO4) and distilled water, yielding various bleaching earths (BEs). The roles of each of the process variables, namely mass fraction of H2SO4 (x) in the dried CaB and pure H2SO4 mixture, heating temperature (T) and contact time (t), in the activation were tested. The raw CaB and each BE were examined with X-ray diffraction, chemical analyses, N2 adsorption/desorption, pH-metry and tintometry. The BE contents in both the aqueous and oily suspensions were set to 2% by mass in order to measure the pH value and the bleaching power, respectively. The optimum conditions for the activation to obtain a BE having the same bleaching power (0.60) as Tonsil® Optimum Bleaching Earth for soybean oil were determined as x = 0.35, T = 100°C and t = 2 h. The bleaching power increased only marginally upon increasing the activation time from 2 h up to 10 h at a given x and T. After 10 h, significant changes did not take place in the bleaching power of the BE. The mass fraction of total structural metal oxide (y), pH value, specific pore volume (V), specific surface area (S) and mean internal diameter (D) of the mesopores for the optimized BE are y = 0.10, pH = 3.0, V = 0.31 cm3 g–1, S = 225 m2 g–1 and D = 7 nm. The pH and D values were more important for bleaching the alkaline refined soybean oil compared to the other parameters tested.

Goosegrass control options in bermudagrass are limited. Topramezone is one option that offers excellent control of mature goosegrass, but application to bermudagrass results in unacceptable symptoms of bleaching and necrosis typical of hydroxyphenylpyruvate dioxygenase inhibitors. Previous research has shown that adding chelated iron reduced the phytotoxicity of topramezone without reducing the efficacy of the herbicide, resulting in safening when applied to bermudagrass. Our objective was to examine additional iron sources to determine whether similar safening effects occur with other sources. Field trials were conducted in the summers of 2016 to 2018 (Auburn University). Mixtures of topramezone and methylated seed oil were combined with six different commercial iron sources, including sodium ferric ethylenediamine di-o-hydroxyphenyl-acetate (FeEDDHA), ferrous diethylenetriamine pentaacetic acid (FeDTPA), iron citrate, FeSO4, and a combination of iron oxide/sucrate/sulfate, some of which contained nitrogen. Bermudagrass necrosis and bleaching symptoms were visually rated on a 0% to 100% scale. Reflectance (normalized difference vegetation index) and clipping yield measurements were also collected. Application of FeDTPA and FeSO4 reduced symptoms of bleaching and necrosis when applied with topramezone. Other treatments that contained nitrogen did not reduce injury but did reduce bermudagrass recovery time following the appearance of necrosis. Inclusion of small amounts of nitrogen often negated the safening effects of FeSO4. The iron oxide/sucrate/sulfate product had no effect on bleaching or necrosis. Data suggest that the iron source had a differential effect on bleaching and necrosis reduction when applied in combination with topramezone to bermudagrass. Overall, FeSO4 and FeDTPA safened topramezone the most on bermudagrass.

POST goosegrass and other grassy weed control in bermudagrass is problematic. Fewer herbicides that can control goosegrass are available due to regulatory pressure and herbicide resistance. Alternative herbicide options that offer effective control are needed. Previous research demonstrates that topramezone controls goosegrass, crabgrass, and other weed species; however, injury to bermudagrass may be unacceptable. The objective of this research was to evaluate the safening potential of topramezone combinations with different additives on bermudagrass. Field trials were conducted at Auburn University during summer and fall from 2015 to 2018 and 2017 to 2018, respectively. Treatments included topramezone mixtures and methylated seed oil applied in combination with five different additives: triclopyr, green turf pigment, green turf paint, ammonium sulfate, and chelated iron. Bermudagrass bleaching and necrosis symptoms were visually rated. Normalized-difference vegetative index measurements and clipping yield data were also collected. Topramezone plus chelated iron, as well as topramezone plus triclopyr, reduced bleaching potential the best; however, the combination of topramezone plus triclopyr resulted in necrosis that outweighed reductions in bleaching. Masking agents such as green turf paint and green turf pigment were ineffective in reducing injury when applied with topramezone. The combination of topramezone plus ammonium sulfate should be avoided because of the high level of necrosis. Topramezone-associated bleaching symptoms were transient and lasted 7 to 14 d on average. Findings from this research suggest that chelated iron added to topramezone and methylated seed oil mixtures acted as a safener on bermudagrass.

The radiocarbon (14C) dating of contaminated old wood has been seen as a challenge requiring many lengthy procedures, often using strong alkali extractions and carbon-containing solvents. Introduced here is a novel protocol called 2chlorOx, a twice-repeated sequence of alkaline hypochlorite and acidic chlorite oxidations, which is shown to work well for 14C and 13C measurements on both <5000 BP and >50,000 BP wood samples, producing results superior to those from conventional acidic chlorite or acidic dichromate oxidations. The 2chlorOx method employs only inorganic reagents, many samples can be completed in less than one day under normal laboratory conditions, and cellulose prepared in this way is usually paper-white in color.

This study focuses on the effects of both thermal treatment (between 80 and 700°C) and chemical activation (concentration of sulfuric acid between 0.3 and 2 M) of natural Ranong kaolins (ground or not) from Thailand to remove the undesirable colour of rice bran oil. The mineralogical, physical and physicochemical properties of the initial and activated kaolins are discussed in relation with the bleaching effectiveness of the activated sample investigated. Generally, the greater the temperature used before the activation step and the concentration of sulfuric acid used during activation, the greater the structural degradation of the kaolinite; Al is removed from the octahedral sheet of kaolinite and amorphous SiO2 dominates the samples. The measured maximum bleaching capacity is not necessarily obtained when using the activated kaolin having the highest specific surface area and pore volume; rather, the bleaching capacity is dependent on both alumina contents and proportion of kaolinite in the samples. Indeed, the partial preservation of the kaolinite structure is crucial to obtain a good bleaching capacity of kaolin in relation to the preservation of the aluminol sites which are likely to be involved in the adsorption of unsaturated molecules present in the rice bran oil. Moreover, as previously demonstrated, a partial leaching of Al from octahedral sheets of kaolin is also an important factor in order to obtain good bleaching capacities. Finally, the optimal preheating temperature and concentration of sulfuric acid which permit the best bleaching capacity of kaolin are reported.

Field experiments were conducted at five sites in Nebraska in 2000 and 2001 to determine the effect of planting depth and isoxaflutole rate on the response of an isoxaflutole-sensitive corn hybrid, ‘Pioneer 33-G’ across variable environments. Corn was planted at depths of 2.5 and 5.0 cm, and isoxaflutole was applied PRE at the recommended (1×) and twice the recommended (2×) rate. The effects of planting depth and herbicide rate on injury varied considerably across site–years. When injury was evident, it was generally greater at the high rate of isoxaflutole (2×) and at the shallow planting depth (2.5 cm). In most site–years, corn recovered from early season injury, and yields were not reduced, except at Scottsbluff, NE, and North Platte, NE, where soils were lower in organic matter and higher in pH. Isoxaflutole rates should be carefully selected for soils with low organic matter and high pH.

Mesotrione, a 4-hydroxyphenylpyruvate dioxygenase-inhibiting herbicide, is labeled for PRE and POST crabgrass control. It has enhanced efficacy on smooth and large crabgrass when applied in conjunction with soil-applied nitrogen (N). The objectives of this study, using crabgrass as the weed species, were to (1) determine the influence of N rate and tissue N concentration on mesotrione activity, (2) determine the influence of N source on mesotrione activity, and (3) determine the influence of N application timing on mesotrione activity. Large crabgrass plants that received 12 kg N ha−1 or more before mesotrione application had more bleached and necrotic leaves compared with plants that received 0 kg N ha−1 7 d after treatment (DAT) in the greenhouse. Although N application rates as high as 98 kg N ha−1 were tested, 90% leaf bleaching and necrosis were observed with rates of 8.9 or 10.1 kg N ha−1 in Tennessee and Indiana, respectively. Nitrogen concentration in large crabgrass leaf and stem tissue on the day of the mesotrione application was closely related to the bleaching and necrosis symptoms observed 7 DAT. Although N rate influenced mesotrione activity, N source did not. Nitrogen application timing was also important, with N applications 3, 1, and 0 d before a mesotrione application having the highest percentage of bleached and necrotic leaves in greenhouse experiments. Both greenhouse and field trials support the finding that N applications in proximity to the mesotrione application enhance herbicide activity. Thus, practitioners can pair N and POST mesotrione applications together or in proximity to enhance crabgrass control.

Knowledge about factors that are important in coral reef growth help us to understand how reef ecosystems react following major anthropogenic and environmental disturbances. In addition, they may help the industry understand how aquarists can improve the health of their corals. I have studied environmental and climate effects on corals on fringing reefs in Jamaica. Radial growth rates (mm/yr) of non-branching corals calculated on an annual basis from 2000–2008 showed few significant differences either spatially or temporally along the north coast, although growth rates tended to be higher on reefs of higher rugosity and lower macroalgal cover. I have also reconstructed recruitment patterns, using growth modelling, for non-branching corals at sites on the north coast of Jamaica near Discovery Bay, and near Kingston Harbour, on the south coast. For all the sites, recruitment of non-branching corals was lowered due to hurricanes or severe storms. For 1560 non-branching corals at sites along the north coast of Jamaica, from Rio Bueno to Pear Tree, there was a significant difference in estimated coral recruitment in years when there were no storms or hurricanes by comparison to years when storms and hurricanes impacted the area. For 347 non-branching corals at sites in the Port Royal Cays on the south coast, there was a significant difference in estimated coral recruitment in years when there were no storms or hurricanes by comparison to years when storms and hurricanes impacted the area. Interestingly, recruitment of Siderastrea siderea on to the side of the ship channel at Rackham's Cay (~100 m from the path taken by large ships) outside Kingston Harbour had been consistent since its construction. These findings have important implications for better understanding the impacts of tropical storms on coral reefs and for aquarists to better maintain coral reef species in artificial environments.

In 1998, in coincidence with high sea surface temperatures, Maldivian reef corals were severely affected by mass mortality following bleaching. Tabular Acropora corals, formerly abundant in shallow water, were nearly exterminated. Recovery started soon, and in 2004 Maldivian reefs appeared rich in tabular Acropora colonies again, especially at some sites. This study aimed at determining the degree of spatial variability of tabular Acropora abundance and size among reef typologies (ocean versus lagoon reefs) and depth zones (4–6, 10–12 and 16–18 m) 6 years after the mass mortality event. A total of 192 tabular Acropora colonies (Ø > 16 cm) were counted and measured in six sites. Their abundance differed between reef typologies and according to depth zones, with the highest values in deep lagoon reefs. Colony mean size differed only among depth zones, the largest colonies (up to 105 cm) being found in shallow reefs. Assuming a radial extension rate of 10 cm · yr−1, colonies larger than 65 cm can be interpreted as the survivors of the mass mortality of 1998; conversely, they may represent the result of enhanced growth rates in uncrowded situations as those characterizing the coral reefs of the Maldives in 2004.

We used suction-pipette recording and fluo-4 fluorescence to study light-induced Ca2+ release from the visible double cones of zebrafish. In Ringer, light produces a slow decrease in fluorescence which can be fitted by the sum of two decaying exponentials with time constants of 0.5 and 3.8 s. In 0Ca2+–0Na+ solution, for which fluxes of Ca2+ across the outer segment plasma membrane are greatly reduced, light produces a slow increase in fluorescence. Both the decrease and increase are delayed after incorporation of the Ca2+ chelator BAPTA, indicating that both are produced by a change in Ca2+. If the Ca2+ pool is first released by bright light in 0Ca2+–0Na+ solution and the cone returned to Ringer, the time course of Ca2+ decline is much faster than in Ringer without previous light exposure. This indicates that the time constants of 0.5 and 3.8 s actually reflect a sum of Na+/Ca2+-K+ exchange and light-induced release of Ca2+. The Ca2+ released by light appears to come from at least two sites, the first comprising 66% of the total pool and half-released by bleaching 4.8% of the pigment. Release of the remaining Ca2+ from the second site requires the bleaching of nearly all of the pigment. If, after release, the cone is maintained in darkness, a substantial fraction of the Ca2+ returns to the release pool even in the absence of pigment regeneration. The light-induced release of Ca2+ can produce a modulation of the dark current as large as 0.75 pA independently of the normal transduction cascade, though the rise time of the current is considerably slower than the normal light response. These experiments show that Ca2+ can be released within the cone outer segment by light intensities within the physiological range of photopic vision. The role this Ca2+ release plays remains unresolved.

The impetus for this study was the mass bleaching event of giant clams in 1997–1998 at several reefs in the Great Barrier Reef (GBR, Australia). From September until December 1999, the study investigated the effects of high light intensities and increased temperature accompanied by a nutrient limitation on the metabolism of Tridacna gigas, to test, if these environmental changes can induce bleaching. In a 50-day trial similar conditions of the mass bleaching event were imitated stressing clams, collected from Orpheus Island and Nelly Bay, by a two- to threefold light intensity and an increased temperature of 4–6 °C. The objectives of the experiments were to determine whether high light intensities can induce changes in chlorophyll content or alter zooxanthella cell sizes and populations in the tissue. After 50 days of exposure to high light intensity the mantle tissue of stressed clams exhibited a decreased number of zooxanthellae per unit area from 19.8 ± 0.8 (× 107·cm–2) to 0.2 ± 0.2 (× 107·cm–2) (mean ± CL). Additionally, the average cell size of zooxanthellae were downsized from 7.4 ± 0.1 μm to 5.3 ± 0.1 μm (mean ± CL). Subsequently, the chlorophyll content of both, chl a and chl c1, declined as well, chl a from 192 ± 4 to 0.1 ± 0.1 μg·ml–1 and chl c1 from 145 ± 6 to 0 μg·ml–1 (mean ± CL). This study shows that increased light intensity and temperature are the main causes for bleaching in giant clams. Thus, the study confirmed the four major aspects involved in bleaching: (1) loss of symbiotic algae, (2) decrease of chl a/c1 in the remaining symbiotic algae, (3) retention of small zooxanthellae in the tissue and (4) release of ammonium (NH4+) into the water column while nutrient uptake of ammonium was largely blocked.